Blender 2.8 textures not showing up in EEVEE and LookDev
WARNING: THIS IS INCORRECT.

This is normal, as these textures are not used in EEVEE. EEVEE only uses the standard "Texture" node, which references the textures in the "Texture" tab of Properties. Unfortunately, Checker Textures cannot be generated in EEVEE.

(THIS IS CORRECT)
I'm not actually sure. (I was thinking of the wrong engine.)